Removing bark from logs, or debarking, is necessary for many industrial uses of wood. In softwood mills, debarking is typically carried out by a ring debarker. Ring debarkers have multiple debarking tools projecting radially inward from a rotating ring. The tips of the debarking tools scrape the surface of individual logs fed through the ring, providing a circumferential scraping action over the surface of the log, tearing the bark from the wood at the cambium layer. A press roll assembly controls the feed speed of the log through the debarker and carries the debarked log downstream for further processing.
Debarking quality can be assessed by various measures including loss of wood fiber, damage to the wood, and bark remaining on the wood. Ensuring that the radial force applied by the debarking tool tips to the log, or debarking force, is appropriate for the log being debarked is important to ensure optimal debarking. Other important operating parameters in addition to debarking force include feed speed of the log through the debarker, and the pressing force applied by the press rolls to the debarked logs. Optimizing these operating parameters can minimize wood fiber loss, damaged wood fiber, and excessive residual bark on the debarked log.
Variations in temperature and moisture content between logs (and even along the length of a particular log) and variation in log species necessitate adjustment of operating parameters to ensure optimal debarking. Logs that are frozen or dry, for example, require application of greater debarking force than logs that are thawed or wet. Temperature and moisture content variations along the length of a particular log can also affect debarking quality. Manual evaluation and adjustment of debarking operating parameters can be imprecise and impractical, particularly in high production, continuous operation environments such as softwood mills.
It is desirable to provide apparatus and methods that automatically and continuously adjust one or more operating parameters of debarking systems to optimize the debarking of logs.